Space Telescope James Webb (JWST) shared this detailed image of distant ice planet Neptune with its clouds, rings and moons last week. The last time Neptune was captured in such detail was more than 30 years ago when the Voyager 2 spacecraft flew past the planet. That is the only space probe to ever visit the planet.
Seen from the sun, Neptune is the farthest planet in the solar system; it is thirty times as far from the sun as the earth is from the sun. At such a great distance, the sun is tiny, making a day on Neptune comparable to a twilight evening on Earth. Winds of up to 1200 kilometers per hour blow. The planet is four times wider than Earth.
Neptune is actually blue, because methane gas in Neptune’s atmosphere absorbs red light and reflects blue light. But in this photo, the planet is purple because JWST observes in the infrared light. That light is invisible to the human eye. In order to show details in the infrared photo well, false colors have been given to the photo. Neptune looks relatively dark because methane gas absorbs infrared light. The lighter patches on the planet are thought to be clouds of methane ice, which do reflect a lot of infrared light. Also clearly visible in the photo are the rings of the planet.
blue spot
The bright blue spot at the top left is not a star, but Neptune’s largest moon, Triton. A layer of nitrogen ice envelops the moon and reflects much infrared light. The six peaks around it are caused by the shape of the mirror of JWST. Triton is the only large moon in the solar system that orbits in the opposite direction to the planet’s rotation.
In addition to Triton, the photo shows six more moons of Neptune. Those are the little white dots between and around the rings. In total, Neptune has fourteen moons.
JWST is the largest and most powerful space telescope ever built. The instrument orbits the sun at a distance of 1.5 million kilometers from Earth.